diff --git a/nova/tests/functional/regressions/test_bug_2088066.py b/nova/tests/functional/regressions/test_bug_2088066.py
new file mode 100644
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+++ b/nova/tests/functional/regressions/test_bug_2088066.py
@@ -0,0 +1,101 @@
+# Copyright (c) 2025, STACKIT GmbH & Co. KG.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import fixtures
+from nova.tests import fixtures as nova_fixtures
+from nova.tests.functional import integrated_helpers
+from nova.tests.functional.libvirt import base
+import threading
+
+
+class TestDeleteInstanceWhileSchedulingWithBDM(
+    base.ServersTestBase, integrated_helpers.InstanceHelperMixin
+):
+    """Regression test for bug 2088066
+
+    This test ensures that when an instance is being booted from an volume
+    and the instance is deleted while still in the scheduling
+    phase, the associated Cinder volume attachments are properly cleaned up.
+    """
+
+    microversion = "latest"
+    CAST_AS_CALL = False
+
+    def setUp(self):
+        super(TestDeleteInstanceWhileSchedulingWithBDM, self).setUp()
+        self.start_compute()
+        self.cinder = self.useFixture(nova_fixtures.CinderFixture(self))
+        self.flavor_id = self.api.get_flavors()[0]["id"]
+
+    def test_delete_instance_while_scheduling_with_bdm(self):
+        sleeping = threading.Event()
+        contd = threading.Event()
+
+        # server booted from volume
+        volume_id = nova_fixtures.CinderFixture.IMAGE_BACKED_VOL
+        server_request = self._build_server(networks=[])
+        server_request.pop("imageRef")  # boot from volume
+        server_request["block_device_mapping_v2"] = [
+            {
+                "boot_index": 0,
+                "uuid": volume_id,
+                "source_type": "volume",
+                "destination_type": "volume",
+            }
+        ]
+
+        # block build_and_run_instance to simulate scheduling delay
+        # so that we can delete the instance while scheduling/building
+        # is in progress
+        def block_build_and_run_instance(*args, **kwargs):
+            sleeping.set()
+            contd.wait()
+            raise NotImplementedError()
+
+        self.useFixture(
+            fixtures.MockPatch(
+                "nova.compute.rpcapi.ComputeAPI.build_and_run_instance",
+                side_effect=block_build_and_run_instance,
+            )
+        )
+
+        # create server (this will block in build_and_run_instance)
+        server = self.api.post_server({"server": server_request})
+        server_id = server["id"]
+        # wait until we are in build_and_run_instance
+        sleeping.wait()
+
+        # now we should have a volume attachment on cinder side
+        cinder_attachments = list(
+            self.cinder.volume_ids_for_instance(server_id)
+        )
+        self.assertNotEqual(
+            [], cinder_attachments, "Should have volume attachments"
+        )
+
+        # delete server and wait for it
+        self._delete_server(server)
+
+        # now check that cinder volume attachments are gone
+        final_attachments = list(
+            self.cinder.volume_ids_for_instance(server_id)
+        )
+        # FIXME: This is a regression check before the fix for bug 2088066
+        self.assertNotEqual(
+            [], final_attachments, "Volume attachments should be cleaned up"
+        )
+
+        # allow build_and_run_instance to continue for clean up (also if this
+        # fails)
+        contd.set()